1. Field of the Invention
The present invention relates to a toner cartridge and to an electrophotographic image forming apparatus. More particularly, the invention is directed to a toner cartridge detachably installed in a developing cartridge. The invention is also directed to an electrophotographic image forming apparatus using the toner cartridge of the invention.
2. Description of the Related Art
In general, in an electrophotographic image forming apparatus, light is illuminated onto a uniformly charged photosensitive medium to form an electrostatic latent image corresponding to a desired image. The electrostatic latent image is developed using a toner to form a toner image. The developed image is thereafter transferred and fixed onto paper to form the desired image.
In particular, colors of yellow Y, magenta M, cyan C, and black K are used in a color image forming apparatus that are overlapped to form a desired color image. The color image forming apparatus, therefore, requires four developers in which toners of the four colors are respectively stored.
The color image forming apparatus including the four developers has not only a larger volume but also a more complex configuration than a monochrome image forming apparatus forming a single color image.
The developer can be classified into a method in which the developer itself is replaced when a toner stored in the developers is used up and a method in which a developing cartridge having a developing roller and a toner cartage storing the toner are separate so that only the spent toner cartridge is replaced when the toner is used up.
When the toner is used up, one method replaces the developer and another method separates the developing cartridge including a developing roller from a toner cartridge for storing the toner and then replaces only the toner cartridge.
When replacing only the toner cartridge, the toner falls by gravity from the toner cartridge into the developing cartridge due to the weight of the toner. The toner cartridge includes a toner outlet for the toner and a shutter which opens and closes the toner outlet. The shutter opens and closes the toner outlet when the toner cartridge is attached to or detached from the developing cartridge.
Since the toner cartridge is separated from the developing cartridge, the toner remaining in the toner outlet may leak to the outside, thereby contaminating the image forming apparatus. In addition, the toner adhered to the shutter may stain a user's hand or clothes.
Therefore, a method is needed for preventing the toner from leaking from the toner cartridge when the toner cartridge is replaced.